SharePoint Migration Best Practices: The Enterprise Planning Guide for 2026

Why Migrate to SharePoint Online in 2026

SharePoint Server 2016 reached end of support in July 2026, and SharePoint Server 2019 enters extended support with limited security patches. Organizations still running on-premises SharePoint face escalating infrastructure costs, security vulnerabilities from unpatched systems, and inability to leverage modern Microsoft 365 capabilities like Copilot, Viva, and Loop. The business case for migration has never been stronger.

At EPC Group, our SharePoint consulting practice has led over 500 enterprise SharePoint migrations — from 100-user departmental moves to 50,000-user global transformations. The organizations that succeed treat migration as a business transformation project, not a technical lift-and-shift.

Key Drivers for Migration

• End of support: SharePoint 2016 end of support (July 2026) eliminates security patches. Running unsupported software creates unacceptable risk for regulated industries.
• Copilot readiness: Microsoft 365 Copilot only works with SharePoint Online content. Organizations that want to leverage AI for document summarization, search, and content creation must have their content in SharePoint Online.
• Infrastructure cost elimination: On-premises SharePoint requires SQL Server licensing, Windows Server licensing, hardware refresh cycles, patching, backup infrastructure, and skilled administrators. SharePoint Online eliminates all of these costs.
• Modern collaboration: SharePoint Online integrates with Teams, OneDrive, Loop, Viva, and Power Platform — creating a unified collaboration experience that on-premises SharePoint cannot match.
• Compliance capabilities: Microsoft Purview retention policies, sensitivity labels, DLP, and eDiscovery work natively with SharePoint Online. On-premises equivalents require separate infrastructure (Exchange hybrid, third-party archiving).

Migration Assessment Framework

The migration assessment is the most critical phase. Skipping or rushing the assessment leads to scope surprises, permission failures, and content loss during migration. EPC Group's assessment framework evaluates five dimensions across the source environment.

Content Audit and Cleanup

Do not migrate everything. The single biggest mistake in enterprise SharePoint migration is migrating all content indiscriminately. Organizations that have run SharePoint for 10-15 years typically accumulate 40-60% of content that is stale (not accessed in 3+ years), duplicated, or no longer relevant. Migrating this content wastes migration bandwidth, increases storage costs, and pollutes search results in the target environment.

Content Classification Framework

Migration Tool Selection

The migration tool landscape has consolidated around a few enterprise-grade options. Tool selection depends on source environment, volume, permission complexity, and budget.

EPC Group's Tool Selection Criteria

• Source environment: ShareGate excels for SharePoint Server to SharePoint Online. SPMT is best for file share migrations and bulk content moves. AvePoint for cross-platform (Google Drive, Box, Dropbox to SharePoint Online).
• Permission fidelity: If maintaining exact permission structures is required (compliance, legal holds), ShareGate provides the most granular permission mapping with pre-migration reports showing permission deltas.
• Incremental migration: All enterprise tools support incremental (delta) migration — only migrating new or changed content on subsequent passes. This is essential for minimizing cutover window duration.
• Reporting: Migration reporting must show success/failure per item, permission mapping results, and throttling events. ShareGate and AvePoint provide the most detailed post-migration reports.

Permission Mapping and Restructuring

Permission migration is where most enterprise migrations encounter the highest complexity and risk. The source environment typically has years of ad-hoc permission assignments, broken inheritance at hundreds of levels, and direct user permissions that do not translate cleanly to SharePoint Online.

Permission Restructuring Approach

EPC Group's approach is to restructure permissions during migration rather than replicating the existing mess. This restructuring follows the principle documented in our SharePoint permissions best practices guide.

1. Audit current state: Run permission reports across all site collections. Identify unique permission scopes, orphaned users, direct user permissions, and nested AD groups.
2. Design target model: Define a target permission model using Microsoft 365 groups and Entra ID security groups. Map business roles to permission levels (Owner, Member, Visitor). Eliminate direct user permissions.
3. Create mapping table: Build a permission mapping table that translates every source AD group and permission level to the target Entra ID group and SharePoint permission level.
4. Validate with stakeholders: Review the permission mapping with site owners and business stakeholders. Confirm no access gaps or over-provisioning in the target model.
5. Test with pilot content: Migrate a representative content subset using the permission mapping. Verify access with test accounts representing different permission levels.

Customization Remediation

SharePoint Online does not support farm solutions, sandbox solutions with server-side code, or SharePoint Designer workflows. Every customization in the source environment requires one of three decisions: remediate (rebuild using modern equivalents), retire (remove the customization), or replace (adopt a third-party solution).

For a detailed guide on modern SharePoint Framework development, see our SPFx development guide. Custom solution remediation typically accounts for 30-40% of total migration budget, so accurate assessment during the discovery phase is critical.

Hybrid Coexistence Strategy

Hybrid coexistence enables users to work across both SharePoint Server and SharePoint Online during the migration period. Microsoft's hybrid features create a seamless experience where users may not notice which environment their content resides in.

Hybrid Features to Configure

• Hybrid search: Cloud Search Service Application (Cloud SSA) indexes on-premises content and returns it alongside SharePoint Online results in a unified search experience. Users search from one location and find content from both environments.
• Hybrid OneDrive: Redirects on-premises MySite personal sites to OneDrive for Business in Microsoft 365. Users clicking "OneDrive" in the on-premises app launcher are redirected to the cloud OneDrive experience.
• Hybrid taxonomy: Synchronizes the managed metadata term store between on-premises and online. Content tagged with managed metadata terms maintains its taxonomy after migration.
• Hybrid auditing: Aggregates audit events from both on-premises and online into the Microsoft 365 unified audit log for consistent compliance reporting during coexistence.
• Hybrid sites: Hybrid sites features include following sites across environments and a unified sites page that shows both on-premises and online sites the user follows.

Cutover Planning and Execution

Cutover is the final migration phase where remaining delta content is migrated, DNS records are updated, and users are redirected to SharePoint Online. Minimizing the cutover window is critical for business continuity.

Pre-Cutover Checklist

• Delta migration complete: Run final incremental migration pass. Verify less than 24 hours of content delta remaining.
• Permission validation: Verify all permission mappings applied correctly. Test access with representative users from each permission group.
• Custom solution testing: Validate all remediated customizations (Power Apps forms, Power Automate flows, SPFx web parts) function correctly in SharePoint Online.
• User communication: Send cutover notification 7 days, 3 days, and 1 day before cutover. Include timeline, expected downtime, and support contact information.
• Rollback plan: Document rollback procedures in case of critical issues. Ensure on-premises SharePoint remains available (read-only) for 30 days post-cutover.
• Support escalation: Staff help desk with trained personnel during the cutover window and the first 5 business days post-cutover.

Cutover Execution Timeline

1. Friday 6:00 PM: Set on-premises sites to read-only. Begin final delta migration pass.
2. Friday 10:00 PM: Final delta migration completes. Run migration validation reports (item count comparison, permission verification).
3. Saturday 8:00 AM: Execute DNS changes and URL redirects. Update any application integrations pointing to on-premises URLs.
4. Saturday 12:00 PM: User acceptance testing with designated testers across all business units.
5. Sunday 6:00 PM: Resolve any identified issues. Finalize go/no-go decision for Monday.
6. Monday 6:00 AM: Full production availability on SharePoint Online. Support team on standby.

Post-Migration Validation

Post-migration validation confirms that content, permissions, metadata, and functionality successfully transferred to SharePoint Online. EPC Group runs a structured validation checklist within 48 hours of cutover.

• Content integrity: Compare item counts between source and target at the site collection, library, and folder level. Investigate any discrepancies. Common causes: file name character restrictions, path length limits, and blocked file types.
• Permission verification: Test access with representative users from each permission group. Verify owners can manage, members can edit, and visitors can only read.
• Search validation: Confirm SharePoint Online search returns content from migrated sites. Verify managed property mappings, result sources, and search verticals.
• Workflow validation: Trigger all migrated/remediated workflows and verify end-to-end execution. Check email notifications, approval routing, and data updates.
• External sharing: Verify external sharing settings match the design. Test B2B guest access to shared sites and documents.
• Compliance features: Confirm retention policies, sensitivity labels, and DLP policies are applied to migrated content. Our data governance team validates compliance configuration as part of every migration.

Partner with EPC Group

EPC Group is a Microsoft Gold Partner with over 500 enterprise SharePoint migrations — from SharePoint 2007 through 2019 to SharePoint Online, and cross-platform migrations from Box, Dropbox, and Google Drive. Our SharePoint consulting team delivers end-to-end migration services — from initial assessment and content audit through tool selection, migration execution, and post-migration optimization. As a bestselling Microsoft Press author of multiple SharePoint books, Errin O'Connor brings unmatched technical depth to every engagement.